Stringed instrument



Jan. 30, 1945. J. w. MCBRIDE STRINGED INSTRUMENT Filed April 20, 1942 2 Sheets-Sheet l INVENTOR J0/7 )44 /V 5nd? BY /f ATTORNEY u t 5 :5:: l c ====v c c :2:: i z n :CEC E c jan. Si), 1945. J. W. MCBRIDE STRINGED INSTRUMENT Filed April 20, 1942 2 Sheets-Sheet 2 Patented Jan. 30, 1945 UNITED STATES PATENT- OFFICE STRIN GED INSTRUMENT John W. McBride, Burbank', Calif. Application April 20, 194,2,l Serial No. 439,647

10 Claims.

This invention` relates to a musical instrument, and especially to one having one or more tensioned strings, such as a guitar, mandolin', violin or the like.

This application is an improvement over three prior applications, filed in the name, of John W. McBride; the first being entitled Stringed musical instrument, and filed onA April 14, 1941, under Serial No. 388,379 which has matured into Patent No. 2,316,799 granted April 20, 1943; the second being entitled Stringed musical instru ment, led on September 14, 1941, under Serial No. 410,813 which has matured into Patent No. 2,316,800 granted April 20, 1943; and the third being entitled Stringed musical instrument and tiled on March` 16, 1942, under Serial No. 434,855.

In these prior applications, there are described mechanisms adapted to be operated by the fingers of a player, for determining the effective length of any of the strings, and thereby to determine the pitchl of the sounds producedby the vibrating strings. The important part of the mechanisms therein described is a rod for each string, and rotatable about an aXis having generally the same direction as the string This rod carries either a continuous or interrupted. helical-like crest or its equivalent. The crest is adapted either to contact the string directly, or else to operater movable frets into string stopping position. The pointy of contact is determined. by the angular positionv of the rod.

It is one of the objects of this invention to pro. vide a different form of device for operating the movable frets, and particularly by the use of a rod that is linearly moved, instead of angularly, as in these prior applications. In general, the operation andy functions of the present embodiment are otherwise similarv to those disclosed in the last of the said prior applications.

This invention4 possesses many other advan tages, and has other objects which may 'be made more easily apparent from a consideration of one embodiment of the invention. For' this purpose there is shown a form in the drawings accompanying and. forming part of the present specilication. This form will now be described in detail, illustrating the general principles of the invention; but it is to be; understood that this detailed description is not to be taken in a. limiting sense, since the scope of this invention is best defined by the appended; claims.

Referring to the drawings:

Figure 1 is a plan View of ing. the invention;

Fig.- 2; is. an enlarged fragmentary sectional a. guitar incorporat- However, the termv string `alcove the neck portion 2.

view taken along the plane 2--2 of Fig. l, parts of the figure being broken away;

Figs. 3 and 4 are sectional Views taken along the. correspondingly numbered planes of Fig. 2;

Fig. 5 is a plan View of' a longitudinally movable cam rod` for operating the movable frets;

Fig, 5A is a diagrammatic representation of the frets in pro-per longitudinal alinement with respect to the cams carried by the rod shown in Fig. 5;

Figs. 6l and 7v are enlargedfragmentary sectional viewstaken respectively along planes i and 'I of Fig. 2'; andv Fig. 8 isv an enlarged fragmentary longitudinal f section illustrating a pair of adjacent frets ln stringI engaging position.

In the present instance the stringed instrument isshown as a guitar', having a' conventional body Iv from which projects Ia; hc-llowed-'out neck portion 2. Ihisneclrl portion terminates (Figs. l and 2l with the peg lboard 3 that accommodates the tuning pegs 4. These tuning pegs 4 are arranged to tension the strings that xt end longitudinally ofthe neck 2` and acrossthe body I. In" the presentY instance there are four string elements, two of which, having; reference numerals and 6, are in the form of singlev strings and the other two, having reference characters 'l and 9, are made up of a pair." of parallel strings (Figs. 3 and 4). as used hereinafter, applies as well` to a plural as Wellv as a single stringstructure. There are six. pegs i corresponding to the six individual strings that extend Each or these strings at the right hand` ends pass over bridge piece 9 andare anchored irr the "body Iv as by theA aid of thepegs Irf. Adjacent the left hand? end of the instrument, asviewedinFigs. l and 2, the strings pass across notches I I` formed, at the top of an upright wall t2. ThisV wall I2 is shown as integrally formed withthe flange I3 accommodated in an appropriate recess in the top oi the board Screws I4 attach the flange I3 in the recess. The wall I.2 and flange |13. form` a partv of a) metallic fret guiding member, thatwill bev described in detailhereinafter;

The body Il of the instrument is shown in this instance as adaptedy toy be provided withA appropriate electrical control` apparatus for the control of tone and Volume. Thus in general, recesses in the` body may be provided to accommodate the volume controlN mechanism I5 as Well as the tone control mechanism.. IiiV (Figi). y Since the present invention. doesI notl relate to these controls, iurther description` thereof is unnecessary.

The strings 5, 8, 1 and 8 are tuned as heretofore stated, by appropriate manipulation of the pegs 4. The particular pitch of vibration of each of the strings is determined by controlling the free length of vibration. This is accomplished by the ald of movable frets, there being in this instance a set of frets for each string. Thus in Fig. 1 there are a series of frets indicated in general by the reference character I1 adapted to cooperate with and engage the double string 8. A similar series I8 of movable frets is adapted to cooperate with the double string 1. Likewise the series of movable frets I9 cooperate with the string 8; and the series of movable frets 28 cooperate with the string 5. These movable frets are arranged below the strings, and move transversely of the length of the string. As indicated most clearly in Fig. l, there are twenty-four frets in each series, corresponding accurately in spacing with the required free lengths of vibration of the strings 5, 8,1 and 8.

The movable frets are all guided for transverse movement in a pair of spaced guide plates 2| and 22 (Figs. 2, 3 and 4). 'I'hese guide plates are spaced immediately below the strings and are supported in a manner now to, be described.

The upper guide plate 2| is shown as being joined integrally at its left hand portion with the upright flange I2.

The right hand end of the upper guide plate 2| is shown as attached by theaid of the screws 23 (Figs. 1 and 2) to the surface 24 slightly recessed below the top surface of the body I. This surface 24 lies adjacent the right hand wall of the recess 24' in the neck 2.

The lower guide plate 22 is held in spaced relation to the upper guide plate 2| by the aid of a plurality of spacers 25, 26 and 21 (Figs. 2 and 4). lar blocks arranged transversely across the plates 2| and 22. As shown most clearly in Fig. 4, bolts 28 may be used to fasten these spacers in position. These bolts pass through the upper and lower guide plates 2| and 22; as well as to the corresponding spacers 25, 28 and 21; they also pass through corresponding transverse supporting plates 29. There are three of these plates 29 respectively disposed below and immediately adjacent the lower guide plate 22. They are utilized (as will be explained hereinafter) for guiding longitudinal movement of the rods that operate the movable frets in the series of frets I1, I8, I9 and 28.

Supporting plates 29 are provided with the four longitudinal grooves 80 corresponding in spacing to the strings 5, 8, 1 and 8. Shallow shoulders are formed adjacent the lower open ends of these grooves 30 for the accommodation of the longitudinally movable operating rods 3|, 32, 33 and 34. The specific structure of these rods and the manner of operation will be explained hereinafter.

A cover plate is provided for each member 29 and serves to provide an uppe'r guiding surface for the longitudinally movable operating rods 3|, 32, 33 and 34. The bolts 28 as shown most clearly in Fig. 4 thus serve to hold the entire assembly of guide plate 2|, spacer 25, guide plate 22, member 29 and cover 35 in assembled relationship.

Each of the movable frets included in the sets I1, I8, I9 and 20, is urged resiliently in a direction away from the corresponding string 5, 8, 1 or 8. The manner in which this is accomplished is seen to best advantage by the aid of Figs. 6

These spacers are in the form of rectangu-v and 8 which illustrate a pair of adjacent frets 38 and 39 cooperating in this instance with the string 6. The fret structure illustrated in Figs. 6 and 8 is typical of all of the other frets and therefore a description of the frets 38 and 39 is sufficient as a description of all of them, except for minor differences to be hereinafter noted.

The frets are of general rectangular cross section, sliding in corresponding rectangular' slots or apertures in the upper and lower guide plates 2| and 22. Intermediate the upper and lower guide plates each fret carries a pin 40. As indicated most clearly in Fig. 8, the ends of the pins are formed as half-round projections to serve as rests for the lower end of the light compression spring 4 I, which encircles the fret. The upper end of the spring is restrained by the lower surface of the upper plate 2|. Its lower end, operating on the flat surfaces of the half-round ends of the pin 48, prevents inadvertent withdrawal of these pins 48. The springs thus urge the frets 38 and 39 downwardly until the pins 48 contact the upper surface of the lower guide plate 22, and out of contact with string 6. This position of the frets is illustrated clearly in Figs. 2 and 7. In Fig. 'I the fret 36 is shown as out of contact with the string 8, the pin 4llresting on the upper surface of the lower guide plate 22.

The frets however may be urged upwardly againstI the force of the springs 4| by the aid of a mechanism now to be described. This mechanism is in the form of the cam rods 3|, 32, 33 and 34 associated with each set of frets I1, Il, I9 or 28, and already referred to in connection with the guiding member 29 illustrated in Fig. 4.

Since these cam rods are identical, but one of them need be described in detail.

Thus in connection with the string 8, there is illustrated a cam rod 32 (Figs. 2 to 8 inclusive). This carn rod carries a plurality oi' crests or cams, extending upwardly out of the plane of the top surface of the rod. A pair of the cams are illustrated by the reference characters 43 and 44 in Figs. 2, 5 and 8. The series of crests as illustrated most clearly in Fig. 5 are arranged in longitudinally spaced relation, and adjacent cams are transversely spaced along the rod 32. In this way even when frets I8 approach very close together, as adjacent the body I, the cams lor operating these closely spaced frets do not interfere with each other. Since the cams 43, 44, etc. are spaced laterally as well as longitudinally along the cam rod 32, each of the frets 38, 39. etc. are provided with lower operating cam follower extensions such as 45 and 46, that are also laterally spaced so as to be in alinement with the corresponding cam with which the fret is to cooperate. Each of the cam follower extensions is provided with a tapered end for effectively co operating with'the corresponding cam.

Considering the frets from left to right as viewed in Fig. 5, the operating extension for fret 38 must be placed quite close to the upper edge of the cam rod 32, in order to aline with the cam 43. On the other hand, the operating ex tension 41 (Figs. 2 and 7) for the fret 36 is placed quite close to the lower edge of the rod 32 as viewed in Fig. 5, in order to aline with the corre sponding cam 48.

These cams 43, 44, etc. may be appropriately formed on the rods 3|, 32, 33 and 34, either integrally or by appropriate attaching means.

Toward the right end of the rod 32 (as shown clearly in Fig. 5), the cams overlap to a greater extent than they do toward the left hand end of aseazsfz 3 the rod. This is due to the fact: that at the` right hand end the frets are necessarily quite closely crowded together. But by virtue of the lateral spacing of the cams, and the lateral spacing of the operating extensions 45, 46, 41, etc. depending from the frets, each of the cams may operate independently of the others.

As shown most clearly in Fig. 2, the rod 32 in its movement toward the right to operate the frets can extend into the recess 49 provided in the body of the instrument, and opening into the main recess 24 of the neck 2.

The crests of the cams 43, 44, etc. are spaced corresponding to the frets 38, 39, etc. Thus they are so arranged that upon continuous movement of the rod 32 from the beginning position illus,- trated in Fig. 2 toward the right, the cams come into Operation in succession, the rst cam 43 becoming active first and the last cam 50 coming last into cooperative relation kwith the last; fret sho-wn in Fig. 5A. The longitudinal position of the rod 32 thus determines which of the cams 43, 44, etc. is active to raise a corresponding fret into contact with the string 6.

The longitudinal movement of the cam rods 3|, 32 33 and 34 is guided in the manner hereinbefore described in connection with Fig. 4, by the aid of. the members 29. Each of these rods 32 is urged resiliently toward the left as viewed in Fig. 2. Thus as shown in Fig. 2, a tension spring 52 is anchored to an upright flange 53 attached to the rod 32. The left hand end of the spring 52 is correspondingly anchored to the downwardly extending wall 54 formed integrally with the upper guide plate 2 I. This wall 54 has a projection 55 extending beneath the springs 52V and providing a surface against which the wall 53 is urged by the spring 52.

The wall 53 is provided with a manually manipulable extension or key 56 which passes through an opening 5T formed in the neck 2 and extending beneath the peg board 3. There is a manually manipulable member or key 56 provided for each of the longitudinally movable cam rods or bars, and each of them is resiliently urged toward the left by a spring identical with spring 52. The projection 55 extends across all of the strings so that it serves as a stop for each and every one of the bars 3|, 32, 33 and 34.

The fingers of the player are intended to co operate with the curved rest 58 projecting upwardly from the key 56.

Rod 32 as heretofore explained, may be urged manually toward the right against the tension of spring 52. Upon urging of rod 32 toward the right, from the beginning position, a position is soon reached (Fig. 8) where cam 44 has not quite reached the position where the fret 39 is raised to its maximum height; andthe cam 43 has just passed its maximum heightl position. By appropriate proportioning of the crests or cams and of the movable frets, this position can be such that both of the frets 36 and 39 are in contact with the string 6. Of course that fret 39 which determines the shorter string length is active to determine the pitch of the string.

Due to the fact that the adjacent frets 39 and 38 are in positions corresponding respectively to cam positions just prior to the maximum height of the fret, and just past the maximum height of the fret, this position of the two frets 38 and 39 is stable. Thus the extension 46 of fret 39 acts against cam 44 to urge rod 32 toward the left, while the pointed extension 45 of fret 38 acts against cam 43 to urge rod 32 toward the right. These opposed forces serve to stabilize the rod position. The player senses this stable position at the. time he is manipulating the device for determining the longitudinal position of the rod 32. A little force at least is required to disturb the stable position illustrated in Fig. 8.

The movement of the frets upwardly to contact the string with which the frets cooperate may be made as sudden as desired by appropriate manipulation; in this way a percussion effect is produced which sets the string into vibration without the necessity of plucking or otherwise manipulating the string. Accordingly it 1s possible to play the instrument by appropriate manipulation of the crested cam rods 3|, 32, 33 and 34.

Ther crested rod 32, heretofore mentioned, is typical of the other crested rods 3|, 33 and 34 cooperating respectively with the series of frets 20, I8 and I'I. Longitudinal guiding of these additional rods is accomplished in the manner clearly illustrated and described in connection with Fig. 4.

As heretofore stated, springs such as 52 illustrated in Fig. 2 urge the cam/rods toward the left. The beginning position for all of the rods (when wall 53 contacts projection 55) is such that a series of transverse frets 59, 69, 6| and 52 are in contact with the corresponding strings '5, 6, and 8. In this way the maximum length of the vibrating strings is determined Iby this transverse seriesr of movable frets 59, 60, 6| and 62.

Upon. release. of the manually operable key member 56, the spring 52 moves the corresponding cam rod toward the left until stopped by the right hand edge of the projection 55. In this movement, each of the cam rods, carries an extreme left hand cam or crest 63 (Figs. 2 and 5) adapted to operate the corresponding fret 59, 60, 6|l or 62. The corresponding fret is thus raised into contact with the corresponding string. Thus in the free position illustrated in Fig. 2, the lfret 6i) is raised into contact with string 6 by the cam 63. Upon movement of the cam rod 32 toward the right by appropriate manual manipulation, thel fret 6.8 is permitted to drop below the string 6 and the operation of the frets takes place as heretofore described. In this way the series of frets 59, 60, 6| and 62 definitely establishes the maximum free vibrating lengths of the corresponding crests. This Aposition is a stable one.

Upon the least movement of the keys 58, etc;

toward the right, the cams such as 63 move toward the right and out of operative relation with the corresponding frets.

In order to. Ifacilitate the positioning of the cam rods 3|, 32, 33 and 34, use is made of scale lines 6'4y (Fig. 5) marked upon the extension `6-5 projecting toward the left from the rod 32. These scale lines may be viewed through a cylindrical magnifying lens 66 mounted in the top guide plate 2|. This cylindrical lens 66 may extend transversely under all of the strings 5, 6, 'I and 8 and may be viewed by the player as he manipulates the keys 58.

A felt pad 61 is disposed on the upper guide plate 2| adjacent frets 59-62, the strings resting upon this pad. This pad '61' forms damping means ensuring against undesired string vilbrations at the left hand portion of the instrument.

What is claimed is:

1. In a stringed musical instrument, a body, a string stretched over the body and having ends attached to the fbody, a movable member for controlling the pitch of a string, means for guiding said member rfor movement longitudinally in the direction of the string, said member having a portion carrying a series of graduations for facilitating adjustment of said member, and a stationary magnifying lens through which the graduations may be viewed.

2. In a. stringed musical instrument, a tensioned string, a plurality of frets movable into contact with the string and spaced along the length of the string, means for guiding the frets for movement in a substantially rectilinear direction transversely of the string, and means cooperating with the frets and movable to cause any of the `frets toengage the string, comprising a longitudinally movable rod extending transversely of the frets, and having raised portions selectively operating the frets.

3. In a stringed musical instrument, a tensioned string, a plurality of frets movable into contact with the string and spaced along the length of the string, means for guiding the frets for movement in a substantially rectilinear direction transversely of the string, and means, cooperating with the frets and movable to cause any ol the frets to engage the string, comprising a longitudinally movable rod extending transversely of the frets, and having raised portions selectively operating the frets, and means continuously urging the frets against said raised portions.

4. In a. stringed musical instrument, a tensioned string, a plurality of frets movable into contact with the string and spaced along the length of the string, means for guiding the frets for movement in a substantially rectilinear direction transversely of the string, and means, cooperating with the frets and movable to cause any of the frets to engage the string, comprising a longitudinally movable rod extending transversely of the frets, and having raised portions selectively operating the frets, and being laterally and longitudinally spaced along said rod.

5. In a stringed musical instrument, a tensioned string, a plurality of frets movable into contact with the string and spaced along the length of the string, means for guiding the frets for movement in a substantially rectilinear direction transversely of the string, and means, cooperating with the frets and movable in a longitudinal direction with respeci-l to the string, to cause any of the frets to engage the string. said means being such that a pair of adjacent frets along the string may be in substantially simultaneous contact with the string.

6. In a stringed 'musical instiument, a tensloned string, a plurality of frets movable into contact with the string and spaced along the length of the string, and means, cooperating with the frets and movable to cause any of the frets to engage the string, comprising a rod movable longitudinally with respect to the string and extending transversely of the frets, and having raised portions constituting crested cams, those raised portions operating on adjacent frets being so displaced longitudinally that both frets may `be moved substantially simultaneously into contact with the string, While the highest parts of the two corresponding cams are displaced respectively on opposite sides of the frets.

7. In a stringed musical instrument, one or more tensioned strings, a guide plate disposed beneath the strings, a plurality of frets for each string and guided for substantially rectilinear movement in apertures in said plate and adapted to engage the strings, and longitudinally movable cam rods, respectively for each string, and ex i tending 'beneath the guide plate, for selectively operating said frets.

8. In a stringed musical instrument, one or more tensioned strings, a pair of apertured plates located below the strings, movable frets for each string guided in alined apertures in said plates, spring means between the plates and urging the frets away from the strings, and means, longitudinally `movable substantially parallel with the respective string, and beneath the plates, for raising the frets selectively into contact with the string.

9. In a stringed Imusical instrument, a tensioned string, a plurality of frets movable into contact with the string and spaced along the length of the string, means for guiding the frets for movement in a substantially rectilinear direction transversely of the string and means cooperating with the frets and movable to cause any of the frets to engage the string, comprising a longitudinally movable rod extending transversely of the frets, and having raised portions selectively operating the frets, and a spring connected to said rod for urging said rod to a limiting position.

l0. In a stringed musical instrument, a tensioned string, a plurality of frets movable into contact with the string and spaced along the length of the string, imeans for guiding the frets for movement in a substantially rectilinear direction transversely of the string and means cooperating with the frets and movable to cause any of the frets to engage the string, comprising a longitudinally movable rod extending transversely of the frets, and having raised portions selectively operating the frets, a manually manipulable member joined to the rod and extending below the rod, and a scale member also attached to the rod and extending above the rod.

JOHN W. MCBRIDE. 

